1. Field of the Invention
The invention relates to a rotating connector for interconnection between at least one fluid passage through a submerged buoy and a pipe system on a floating vessel for the production of hydrocarbons, comprising a pair of cooperating, fluid-transferring swivel members in the form of a female member and a male member which may be introduced axially into or withdrawn from each other, the female member being permanently fixed to the buoy, and an electrohydraulic swivel constituting a part of the male member and being arranged for transfer of electrical power and electrical and hydraulic control signals, the swivel members at their lower ends comprising cooperating connector parts for interconnection of respective power, signal and hydraulic lines from the swivel and from the buoy.
2. Discussion of the Prior Art
A rotating connector or coupling device comprising cooperating swivel members of the above-mentioned type for example is known from Norwegian patent application No. 932460. This application describes a system for offshore production of hydrocarbons by means of a vessel which is arranged for quick connection to or disconnection from a submerged buoy, where the buoy is of the type comprising a bottom-anchored centre member which is connected to a number of risers extending up to the buoy, and an outer buoyancy member which is rotatably mounted on the centre member and may be introduced and locked in a submerged downwardly open receiving space in the vessel. At the upper end of the buoy there is arranged a rotating coupling or swivel device of the stated type, wherein the swivel members define mutually sealed annular spaces or annuluses communicating with associated fluid paths in the swivel members, for the transfer of process fluid and possible injection fluids between the risers and a pipe system on the vessel. The female swivel member is permanently fixed to the centre member of the buoy whereas the male member is connected to an operating means on the vessel, so that the swivel members may be introduced into and withdrawn from each other by the operating means, the swivel members defining said annuluses in interconnected condition. On each side of the annuluses there is provided for sealing means which may be activated by means of a pressure fluid to form a seal between the annuluses, and which may be relieved in case of mutual disconnection of the swivel members.
An electrohydraulic swivel which is arranged such as stated in the introduction, is not described in said patent application. However, such an arrangement lately has become known in the market in connection with the development and production of the introductorily stated connector. In the known device the electrohydraulic swivel is arranged at the lower end of the device and is constructed for the transfer of electrical power at intermediate voltages, i.e. of the order of 1000 volts. However, in operation of production vessels of the topical type it is desirable to be able to transfer electrical power of a substantially higher value than with the known connector, e.g. 10-12 MVA or higher. The corresponding voltage and current values in three-phase transmission may be about 11 kV and 600 A, or higher. An electrohydraulic swivel for the transfer of such a high electrical power requires a larger space than what is allowed by the known connector. Further, the known arrangement is not so flexible as desirable as regards the possibility to satisfy special customer specific demands and needs. In addition, in order to satisfy the demands to security in the topical operating environment, there is a need to take special precautionary measures, in order to avoid explosion hazard.